The present invention relates to the field of removing Chemical Mechanical Polishing (CMP) residue from semiconductor wafers. More particularly, the present invention relates to the field of removing CMP residue from semiconductor wafers using supercritical carbon dioxide.
Manufacture of semiconductor devices commonly employ a Chemical Mechanical Polishing (CMP) process to planarize a wafer surface. The CMP process removes top surface layers from a semiconductor wafer. The CMP process leaves a CMP residue of CMP chemicals and particles that is difficult and problematic to remove by current post-CMP cleaning methods. It is well known that the CMP residue predominantly remains in surface features on the wafer surface.
The current post-CMP cleaning methods require that the wafer surface be mechanically washed or brushed by a commercially available machine called a scrubber. The scrubber may employ heat or ultrasonic augmentation and typically requires immersion times of two to twenty minutes to achieve complete removal of the CMP residue from the wafer surface. Because the wafer surface is mechanically washed or brushed by the scrubber, the scrubber leaves defects or scratches in the wafer surface.
It is well known that, if some of the CMP residue remains in the surface features, performance of the semiconductor devices will be degraded. Additionally, it is well known that the cost of manufacturing a wafer of the semiconductor devices is proportional to the time employed for each processing step.
It would be advantageous to be able to remove the CMP residue without using the mechanical washing or brushing employed by the scrubber in order to reduce an amount of the defects and the scratches. Further, it would be advantageous to more effectively remove the CMP residue from the surface features on the wafer surface.
What is needed is a method of removing the CMP residue that does not use the mechanical washing or brushing.
What is further needed is a method of removing the CMP residue that is more effective than the mechanical washing or brushing in removing the CMP residue from the surface features.
What is additionally needed is a method of removing the CMP residue that is more efficient than the scrubber.
The present invention is a method of removing Chemical Mechanical Polishing (CMP) residue from a surface of a semiconductor substrate. The semiconductor substrate, including the CMP residue on the surface, is placed within a pressure chamber. The pressure chamber is then pressurized. Supercritical carbon dioxide and a solvent are introduced into the pressure chamber. The supercritical carbon dioxide and the solvent are maintained in contact with the semiconductor substrate until the CMP residue is removed from the semiconductor substrate. The pressure chamber is then flushed and vented.